INHERITANCE AND CHARACTERIZATION OF A DARK-GERMINATING, LIGHT-INHIBITED MUTANT IN THE FERN CERATOPTERIS-RICHARDII

Selection for a dark-germinating mutant was made with X-irradiated spores of Ceratopteris richardii. A single mutant line (H-alpha-DG1) was recovered and analyzed for its germination responses under different light-dark treatments and for transmission of the trait through a complete sexual cycle. H-alpha-DG1 was characterized by two phenotypes, dark germination and light inhibition of germination. These responses were exactly opposite from wild-type responses. The level of dark germination for a particular spore batch was stable through time, whereas light inhibition was unstable with time. Genetic analysis indicated that both phenotypes are associated with a single nuclear gene mutation that has been designated dkg1.